Electrosurgical instrument and method

ABSTRACT

An electrosurgical working end and method for sealing and transecting tissue. An exemplary working end provides curved jaw members that are positioned on opposing sides of the targeted anatomic structure. The working end carries a slidable extension member having flange portions with inner surfaces that slide over the jaw members to clamp tissue therebetween. The working end carries an independent slidable cutting member that is flexible to follow the curved axis of the jaws. The electrosurgical surfaces of the jaws include partially-resistive bodies for carrying a current or load which modulates ohmic heating in the engaged tissue to prevent charring and desiccation of tissue to create a high strength thermal seal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a divisional of U.S. patentapplication Ser. No. 11/173,878, filed on Jul. 2, 2005, now U.S. Pat.No. 8,075,558, which a Continuation-in-Part of U.S. patent applicationSer. No. 10/136,874 filed Apr. 30, 2002, now U.S. Pat. No. 6,913,579.This application also is related to the following co-pending U.S. patentapplication Ser. No. 10/032,867 filed Oct. 22, 2001, now U.S. Pat. No.6,929,644, Ser. No. 10/308,362 filed Dec. 3, 2002 now U.S. Pat. No.6,770,072, and Ser. No. 10/291,286 filed Nov. 9, 2002, now U.S. Pat. No.6,926,716. The entire contents of the above-listed patent applicationsare incorporated herein by this reference and should be considered apart of this specification.

FIELD OF THE INVENTION

This invention relates to medical devices and techniques and moreparticularly relates to the working end of an electrosurgical instrumentthat is adapted for sealing and transecting tissue.

BACKGROUND OF THE INVENTION

In various open and laparoscopic surgeries, it is necessary to seal orweld the margins of transected tissue volumes and transected bloodvessels. However, satisfactory instruments have not been developed forelectrosurgically excising a tissue biopsy sample from a lung or liver,for example, that seal the margin of the targeted structure while at thesame time preventing gross thermal damage to the resected tissue sample.

As background, various radiofrequency (Rf) surgical instruments havebeen developed for sealing the edges of transected tissues. For example,FIG. 1A shows a sectional view of paired electrode jaws 2 a and 2 b of atypical prior art bi-polar Rf grasper grasping two tissue layers. In atypical bi-polar jaw arrangement, each jaw face comprises an electrodeand Rf current flows across the tissue between the first and secondpolarities in the opposing jaws that engage opposing exterior surfacesof the tissue. FIG. 1A shows typical lines of bi-polar current flowbetween the jaws. Each jaw in FIG. 1A has a central slot adapted toreceive a reciprocating blade member as is known in the art fortransecting the captured vessel after it is sealed.

While bi-polar graspers as in FIG. 1A can adequately seal or weld tissuevolumes that have a small cross-section, such bi-polar instruments areoften ineffective in sealing or welding many types of anatomicstructures, e.g., (i) anatomic structures having walls with irregular orthick fibrous content, such as lung tissue; (ii) bundles of disparateanatomic structures, and (iii) substantially thick anatomic andstructures.

As depicted in FIG. 1A, a prior art grasper-type instrument is depictedwith jaw-electrodes engaging opposing side of a tissue volume withsubstantially thick, dense and non-uniform fascia layers underlying itsexterior surface. As depicted in FIG. 1A, the fascia layers f prevent auniform flow of current from the first exterior tissue surface s to thesecond exterior tissue surface s that are in contact with electrodes 2 aand 2 b. The lack of uniform bi-polar current across the fascia layers fcauses non-uniform thermal effects that typically result in localizedtissue desiccation and charring indicated at c. Such tissue charring canelevate impedance levels in the captured tissue so that current flowacross the tissue is terminated altogether. FIG. 1B depicts an exemplaryresult of attempting to create a weld across tissue with thick fascialayers f with a prior art bi-polar instrument. FIGS. 1A-1B showlocalized surface charring c and non-uniform weld regions w in themedial layers m of vessel. Further, FIG. 1B depicts a common undesirablecharacteristic of prior art welding wherein thermal effects propagatelaterally from the targeted tissue causing unwanted collateral (thermal)damage indicated at d.

What is needed is an instrument working end that can utilize Rf energy(i) to transect tissue about a curved path; (ii) to provide a seal intissue that limits collateral thermal damage; and (iii) to provide aseal or weld in substantially thick anatomic structures and tissuevolumes that are not uniform in hydration, density and collagenouscontent.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an instrument workingend capable of transecting and compressing tissue to allow forcontrolled Rf energy delivery to transected tissue margins that havethick fascia layers or other tissue layers with non-uniform fibrouscontent. Such tissues are difficult to seal since the fascia layers canprevent uniform current flow and uniform ohmic heating of the tissue.

As background, the biological mechanisms underlying tissue fusion bymeans of thermal effects are not fully understood. In general, thedelivery of Rf energy to a captured tissue volume elevates the tissuetemperature and thereby at least partially denatures proteins in thetissue. The objective is to denature such proteins, including collagen,into a proteinaceous amalgam that intermixes and fuses together as theproteins renature. As the treated region heals over time, the biologicalweld is reabsorbed by the body's wound healing process.

In order to create an effective weld in a tissue volume dominated by thefascia layers, it has been found that several factors are critical. Theobjective is to create a substantially even temperature distributionacross the targeted tissue volume to thereby create a uniform weld orseal. Fibrous tissue layers (i.e., fascia) conduct Rf currentdifferently than adjacent less-fibrous layers, and it is believed thatdifferences in extracellular fluid contents in such adjacent tissuescontribute greatly to the differences in ohmic heating. It has beenfound that by applying high compressive forces to fascia layers andunderlying non-fibrous layers, the extracellular fluids migrate from thesite to collateral regions. Thus, the compressive forces can makeresistance more uniform regionally within engaged tissue.

Another aspect of the invention provides means for creating highcompression forces along the very elongate working end of the inventionthat engages the targeted tissue. This is accomplished by providing aslidable or translatable extension member that defines cam surfaces thatengage the entire length of jaw members as the translatable member isextended over the jaws. The translatable member of the invention thus isadapted to perform multiple functions including contemporaneouslyclosing the jaws and transecting the engaged tissue, applying very highcompression to the engaged tissue, and cooperating with electrosurgicalcomponents of the jaws to deliver thermal energy to the engaged tissue.

The combination of the translatable extension member in cooperation withthe curved jaws thus allows for electrosurgical electrode arrangementsthat are adapted for controlled application of current to engagedtissue. An exemplary electrosurgical instrument includes anopenable-closeable jaw assembly with first and second jaw members withelectrosurgical energy-delivery surfaces, wherein each jaw includes anopposing polarity conductive body coupled to an electrical source, andwherein at least one jaw surface includes a partially resistive bodyselected from the class consisting of a body having a fixed resistance,a body having resistance that changes in response to pressure and a bodyhaving resistance that changes in response to temperature. In theseembodiments, the partially resistive body capable is of load-carrying toprevent arcing in tissue about the energy-delivery surfaces to createand effective weld without charring or desiccation of tissue.

In another embodiment of the invention, the working end includescomponents of a sensor system which together with a power controller cancontrol Rf energy delivery during a tissue welding procedure. Forexample, feedback circuitry for measuring temperatures at one or moretemperature sensors in the working end may be provided. Another type offeedback circuitry may be provided for measuring the impedance of tissueengaged between various active electrodes carried by the working end.The power controller may continuously modulate and control Rf deliveryin order to achieve (or maintain) a particular parameter such as aparticular temperature in tissue, an average of temperatures measuredamong multiple sensors, a temperature profile (change in energy deliveryover time), or a particular impedance level or range.

Additional objects and advantages of the invention will be apparent fromthe following description, the accompanying drawings and the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the present invention will be understoodby reference to the following detailed description of the invention whenconsidered in combination with the accompanying Figures, in which likereference numerals are used to identify like components throughout thisdisclosure.

FIG. 1A is an illustration of current flow between the paired jaws of aprior art bi-polar radiofrequency device in a method of sealing a tissuewith fascia layers that are resistant to Rf current flow therethrough.

FIG. 1B illustrates representative weld effects of the bi-polar currentflow of FIG. 1A.

FIG. 2 is a view of an exemplary Type “A” working end corresponding tothe present invention showing first and second jaw members extendingfrom the distal end of an introducer body (phantom view), with acooperating translatable extension member in a first non-extendedposition within the introducer body.

FIG. 3 is a perspective view of the proximal portions of the extendingmember that carry the paired jaws and a portion of the translatablemember taken along line 3-3 of FIG. 2.

FIGS. 4A-4C are illustrations of the steps of practicing the method ofthe invention with the working end of FIG. 2:

FIG. 4A depicting the positioning of the paired jaws over a targetedportion of a patient's lung;

FIG. 4B depicting the advancement of the translatable member over thejaw members to (i) transect the tissue to provide a biopsy sample and(ii) compressing the remaining tissue margin tightly between the jawmembers for electrosurgical sealing; and

FIG. 4C providing a sectional view taken along line 4C-4C of FIG. 4B toillustrate the path of Rf current flow through medial layers of thecaptured tissue.

FIG. 5 is a view of the components of a Type “B” working end wherein thejaws and translatable member provides a different electrode arrangementfor sealing tissue.

FIG. 6 is a perspective view of an alternative embodiment with a handleportion coupled to an elongated introducer member having a working endthat carries a curved jaw structure.

FIGS. 7A-7C are plan views of the working end of the instrument of FIG.6 in different stages of operation; FIG. 7A depicting a translatablemember for closing the jaws in a non-extended position; FIG. 7Bdepicting the translatable member in an extended position that closesthe jaws; and FIG. 7C depicting a blade member in an extended positionto cut tissue engaged by the jaws.

FIG. 8A is a perspective cut-away view of the working end of FIGS. 7A-7Cin a jaw-closed position.

FIG. 8B is a cut-away view of the working end of FIGS. 7A-7C with thecutting member in an extended position for cutting tissue.

FIG. 9A is a plan view of an alternative embodiment of working end thatcarries a curved jaw structure.

FIG. 9B is a cut-away view of the working end of FIG. 9A.

FIG. 10 is a schematic sectional view the first and second jaws of theworking end of FIGS. 7A-7C and FIGS. 8A and 8B illustrating an exemplaryconfiguration of electrosurgical energy-delivery surfaces.

FIG. 11 is a schematic sectional view of alternative first and secondjaws similar to FIG. 10 with a different configuration ofelectrosurgical energy-delivery surfaces.

FIG. 12 is a schematic view of alternative of first and second jaws withanother configuration of electrosurgical energy-delivery surfaces.

FIG. 13 is a schematic view of alternative of first and second jaws withanother configuration of electrosurgical energy-delivery surfaces

FIG. 14 is a schematic view of alternative of first and second jaws withyet another configuration of electrosurgical energy-delivery surfaces

DETAILED DESCRIPTION OF THE INVENTION

1. Type “A” working end for tissue transection. Referring to FIG. 2, theworking end 10 of an exemplary Type “A” embodiment is shown that isadapted for electrosurgically transecting a volume of tissue from apatient's lung or other targeted structure while at the same timesealing the transected tissue margin. The working end 10 comprises anintroducer body portion 11 (phantom view) that extends from a proximalbody end 12 a to a distal body end 12 b along longitudinal axis 15. Inthe exemplary embodiment of FIG. 2, the introducer body 10 can have acylindrical or oval cross-section and comprises a thin-wall tubularsleeve 16 that extends from any suitable handle (not shown). Thediameter of sleeve 16 can range from about 5 mm. to 10 mm., althoughother diameter instruments fall within the scope of the invention. Thehandle may be any type of pistol-grip or other type of handle known inthe art that carries an actuator lever or slide to extend thetranslatable member 40 over first and second jaws 22 a and 22 b as willbe described below.

As can be seen in FIG. 2, the paired jaw members 22 a and 22 b areformed to extend substantially rigidly about a curved axis indicated 25that is defined by the jaw's cooperating engagements surfaces 26 a and26 b in the closed position when engaging tissues. FIGS. 2-3 show thatthe independent jaw members 22 a and 22 b comprise the distal portion ofelongate extension rod members 28 a and 28 b that extend from theinstrument handle. The extensionmembers 28 a and 28 b can have across-section ranging from about 0.05″ to 0.20″ and can have a flatsurface so that the paired members can be slidably received by bore 30in translatable member 40. The extension members and jaws 22 a and 22 bare formed of a suitable metal rod material with the flattenedengagements surfaces 26 a and 26 b having serrations 41 another grippingsurface for gripping tissue. It should be appreciated that curvedportions of jaws 22 a-22 b can have any suitable radius or curve fortransecting tissue of a selected dimension.

Of particular interest, FIGS. 3 and 4 illustrate a translatable member40 that is adapted to perform multiple functions: (i) to provide alaterally-flexing cam mechanism that can slide over the curved jaws tothereby highly compress engagement surfaces 26 a and 26 b againstopposing sides of the targeted tissue T; (ii) to contemporaneouslytransect the targeted tissue along a path p that is defined by theengagement axis 25 of the jaws, and (iii) in some embodiments, to carryelectrode arrangements that can cooperate jaw electrodes to seal themargin of the transected tissue.

FIG. 3 shows a perspective view of translatable member 40 andillustrates the manner in which the member is flexible so as to bendlaterally to slide over the curved jaw members 22 a and 22 b (see FIG.2) while at the same time providing cam surfaces for moving the jaws tothe closed tissue-engaging position from the open position. In thisexemplary embodiment, the translatable member 40 can be fabricated froma metal tubular material with sections removed therefrom or can befabricated by plastic injection molding. No matter the material, thecomponent comprises a laterally-flexing backbone portion indicated at 44that is connected to jaw-engaging sections 45 (collectively) that arespaced apart along the backbone and separated by cuts or scallops 48(collectively).

It can easily be seen how the translatable member 40 can bend laterallyas depicted by the arrow in FIG. 3 to follow the curves of jaws 22 a-22b. More in particular, this embodiment shows that jaw-engaging sections45 comprise upper and lower “c”-shaped portions or flanges 50 a and 50 bthat define inner surfaces 52 a and 52 b for slidably engaging the jaws22 a and 22 b about outward surfaces 62 a and 62 b of the jaws (FIG. 2).In this embodiment, the inner cam surfaces 52 a-52 b of translatablemember 40 have a part-round cross-section to slidably cooperate with therounded surfaces 62 a-62 b of the jaws, but it should be appreciatedthat any cooperating shapes are possible as long as the cam surfaces 52a-52 b wrap partially (laterally) around the jaw members to insure thatthe “c”-shaped portions 50 a-50 b will track over the curved jaws asthey compress the targeted tissue.

As can be seen in FIG. 3, the extension members and jaws 22 a and 22 bin the closed position define a dimension D between the engagementsurfaces 26 a and 26 b which is selected as appropriate for engaging andcompressing the targeted tissue, which is typically quite narrow andselected for the particular targeted tissue. In order to insure that the“c”-shaped portions 50 a-50 b of the translatable member 40 havesufficient strength to maintain their shape without flexing in order tocompress the jaws over the targeted tissue, the cross-section ofjaw-engaging sections 45 is made sufficiently thick or with any suitablereinforcing shown for additional strength.

Now turning to the electrosurgical functionality of the invention, FIG.3 shows that distal termination 64 of the translatable member 40 carriesan electrode cutting element indicated at 65. In the exemplaryembodiment of FIG. 3, the translatable member 40 is of a moldednon-conductive material and electrode 65 is coupled to electrical source70 and controller 75 by electrical lead 76 that extends through backboneportion 44 of member 40. If the translatable member 40 is of aconductive metal, the distal cutting electrode 65 is insulated from themember as is known in the art, for example by providing an electrodecarried over a thin insulated film backing.

Still referring to FIG. 3, it can be seen that translatable member 40 isfurther carries an electrode arrangement for sealing the tissue margincaptured between the jaws 20 a-20 b. More in particular, member 40 hascooperating electrode surface portions 80 and 85 a-85 b that are exposedto contact the captured tissue: (i) at the transected medial tissue thatinterfaces the medial electrode 80, and (ii) at opposed exteriorsurfaces of the captured tissue that contacts the outboard electrodes 85a-85 b, respectively (see FIG. 4C). For purposes of illustration, theexposed electrode surface portions 80 and 85 a-85 b are indicated inFIG. 3 to have a positive polarity (+) and negative polarity (−). Theseopposing polarity electrodes are, of course, spaced apart from oneanother and coupled to the electrical source 70 that defines thepositive and negative polarities during operation of the instrument. Themedial electrode 80 is coupled to electrical source 70 and controller 75by lead 86 that extends through backbone portion 44 of the member. Theoutboard electrodes 85 a-85 b are similarly coupled to electrical source70 and controller 75 by leads 87 a and 87 b. In the exemplary embodimentof FIG. 3, the extension members and jaw members 20 a-20 b have aninsulative coating indicated at 88 so as to not provide a conductivepath between the active electrodes.

Now turning to FIGS. 4A-4C, the operation and use of the working end 10of FIG. 2 in performing a method of the invention can be brieflydescribed as follows. FIG. 4A depicts the working end being positionedover an edge of a patient's lung L or other body structure where theobjective is to remove a tissue sample indicated at T. FIG. 4B shows thetranslatable member 40 being advanced from its non-extended (linear)position to its extended and curved distal position as it ramps over thetissue by advancing over the jaws members 20 a-20 b that compress thetissue just ahead of the advancing member 40. The laterally-outwardportions of the translatable member 40 thereby slide over and engage thejust-transected tissue margin m contemporaneous with cutting electrode65 transecting the tissue. By this means, the tissue margin m iscaptured under high compression by the cooperating components of theworking end 10. FIG. 4B also shows the tissue sample T being resectedfrom the lung.

FIG. 4C depicts the tissue margin m captured between jaws members 20a-20 b and upper and lower portions of the jaw-engaging sections 45 ofmember 40. The tissue margin m may be any soft tissue or anatomicstructure of a patient's body. In this example, the tissue is shown witha surface or fascia layer indicated at f and medial tissue layers mt.FIG. 4C provides an illustration of one preferred manner of Rf currentflow that causes a sealing or welding effect by the medial-to-surfacebi-polar current flow (or vice versa) indicated by arrows A. It has beenfound that a substantially uniform weld can be created across thecaptured tissue margin by causing current flow from exposed medialelectrode surface 80 to electrodes 85 a and 85 b. In other words, thesectional illustration of FIG. 4C indicates that a weld can be createdin the captured tissue margin where proteins (including collagen) aredenatured, intermixed under high compressive forces, and fused uponcooling to seal or weld the transected tissue margin. Further, thedesired weld effects can be accomplished substantially withoutcollateral thermal damage to adjacent tissues indicated at ct in FIG.4C.

Another embodiment of the invention (not shown) includes a sensor arrayof individual sensors (or a single sensor) carried in any part of thetranslatable member 40 or the jaws 20 a-20 a that contact engagedtissue. Such sensors preferably are located either under an electrode oradjacent to an electrode for the purpose of measuring temperatures ofthe electrode or tissue adjacent to an electrode during a weldingprocedure. The sensor array typically will consist of thermocouples orthermistors (temperature sensors that have resistances that vary withthe temperature level). Thermocouples typically consist of paireddissimilar metals such as copper and constantan which form a T-typethermocouple as is known in the art. Such a sensor system can be linkedto feedback circuitry that together with a power controller can controlRf energy delivery during a tissue welding procedure. The feedbackcircuitry can measure temperatures at one or more sensor locations, orsensors can measure the impedance of tissue, or voltage across thetissue, that is engaged between the electrodes carried by the workingend. The power controller then can modulate Rf delivery in order toachieve (or maintain) a particular parameter such as a particulartemperature in tissue, an average of temperatures measured amongmultiple sensors, a temperature profile (change in energy delivery overtime), a particular impedance level or range, or a voltage level as isknown in the art.

2. Type “B” working end for tissue transection. Referring to FIG. 5,components of a Type “B” working end 110 are shown that again areadapted for transecting and welding a tissue margin. This embodimentoperates as described previously with translatable member 140 adapted toslide over the jaws 20 a and 20 b and again carries distal cuttingelectrode 65. However, in this embodiment, each jaw member 20 a and 20 bis coupled to electrical source 70 and controller 75 by electrical leads147 a and 147 b to function as paired bi-polar electrodes with positivepolarity (+) and negative polarity (−) indicated in FIG. 5. The pairedjaw-electrodes themselves deliver Rf energy to the tissue which can besuitable for tissues that have substantially thin fascia layers and thathave uniform collagenous content.

In another embodiment (not shown) the translatable member can carry atleast one electrode as depicted in FIG. 3 to cooperate with the activeelectrode jaws of FIG. 5. The controller 75 then can multiplex the Rfcurrent flow along different selected paths among spaced apartelectrodes as described in co-pending U.S. patent application Ser. No.09/792,825 filed Feb. 24, 2001 titled Electrosurgical Working End forTransecting and Sealing Tissue, now U.S. Pat. No. 6,533,784, which isincorporated herein by reference. While FIGS. 2-5 depict an exemplaryembodiment that uses a high-voltage cutting electrode to transecttissue, it should be appreciated that the cutting element also can be asharp blade member.

FIG. 6 illustrates an alternative embodiment of instrument 200 forsealing and transecting tissue that includes handle 205 coupled to anelongate introducer member 206 that extends to working end 210A. Theworking end 210A again comprises an openable-closeable jaw assembly withcurved first and second jaws 222 a and 222 b that close and engagetissue about a curved axis indicated at 225. The introducer 206 has acylindrical or rectangular cross-section and can comprises a thin-walltubular sleeve that extends from handle 205. The handle has lever arm228 that is adapted to actuate and translate the translatable member 240and an independent tissue cutting member 245 as will be described below.The Rf source 70 and controller 75 are coupled to the handle 205 by acable 246 and connector 248.

The embodiment of FIG. 6 is configured differently than the previousembodiments in that the translatable member 240 for closing the curvedjaw members 222 a and 222 b is not laterally flexible. However, thetissue-cutting member 245 is flexible thus allowing the blade's cuttingpath to follow a curve defined by the curved axis about which the jawsclose. The linear stroke S of the translatable member 240 is shown inFIG. 7A-7C and FIGS. 8A-8B wherein the cam surfaces of translatablemember 240 extend only over a proximal linear portion 249 of the jaws.

Turning to FIG. 8A, it can be seen that translatable member 240 againhas upper and lower flanges or “c”-shaped portions 250 a and 250 b thatdefine inner cam surfaces 252 a and 252 b for slidably engagingoutward-facing surfaces 262 a-262 b of jaws 222 a and 222 b. The innercam surfaces 252 a and 252 b of translatable member 240 can have anysuitable profile to slidably cooperate with surfaces 262 a-262 b of thejaws. As can be seen in FIG. 8A-8B, the jaws 222 a and 222 b in theclosed position define a gap or dimension D between the jaws'energy-delivery surfaces 265 a and 265 b which equals from about 0.0005″to about 0.005″ and preferably between about 0.001″ about 0.002″. Theedges 268 of the energy-delivery surfaces 265 a and 265 b are rounded toprevent the dissection of tissue. A space or channel 270 is providedbetween the jaws and transverse surface 272 of translatable member 240to accommodate the sliding movement of tissue-cutting member 245.

FIGS. 7A-7C illustrate the combined actuation of translatable member 240for closing the curved jaw members and the actuation of tissue-cuttingmember 245 for transecting the engaged and sealed tissue. FIG. 7Adepicts a view from above of jaws 222 a and 222 b engaging tissueindicated at T before the jaws are closed. FIG. 7B illustrates thetranslatable member 240 being advanced from its non-extended position toan extended position (or stroke S) as inner cam surfaces 252 a and 252 bof translatable member 240 advance over the outer surfaces of linearsection 249 of the jaws (see FIG. 8A). The actuation of translatablemember 240 is caused by moving lever arm 228 over the range of motionindicated at A in FIG. 6.

FIG. 7C illustrates the tissue-cutting member 245 with a sharp bladeedge 274 being advanced from a non-extended position to its extendedposition to cut the engaged tissue T. As can be seen in FIG. 7C and 8B,the blade edge 274 advances beyond the distal end 276 of translatablemember 240. The tissue-cutting member 240 is a thin flexible metal thatallows it to flex and follow the curvature of the jaws. The actuation oftissue-cutting member 240 is caused by moving lever arm 228 over therange of motion indicated at B in FIG. 6.

In a method of use, the application of electrosurgical energy to theengaged tissue can occur contemporaneously with jaw closure andadvancement of cutting member 245, or after closing the jaws. Thecontroller can be programmed to deliver energy automatically uponadvancement of the cutting member 245 or the system can be provided withan independent on-off footswitch for energy delivery.

FIGS. 9A-9B illustrate an alternative working end 210B for sealing andtransecting tissue that again includes curved first and second jaws 222a and 222 b that close and engage about a curved axis. This embodimentis configured for sealing both sides of transected tissue and thus hasenergy-delivery surfaces 265 a and 265 b that extend on both sides ofchannel 280 in the jaws that slidably accommodates the transverseelement 282 of the translatable member 240. As can be seen in FIG. 9B,the cross-section of translatable member 240 has a configuration similarto an I-beam. Flange portions 250 a and 250 a′ extend across the upperportion of translatable member 240 and flange portions 250 b and 250 b′extend across the lower portion of the translatable member 240. TheI-beam configuration for closing electrosurgical jaws under highcompression is described in co-pending application Ser. No. 10/032,867and Ser. No. 10/308,362 which are incorporated herein by this reference.As can easily understood from FIGS. 9A-9B, the translatable member 240can be translated axially over the linear portion 249 of jaws 222 a and222 b until it reaches the limit of its stroke to close the jaws.Thereafter, the blade member 245 is advanced to transect the engagedtissue.

Now turning FIGS. 10-14, various embodiments of electrosurgicalenergy-delivery surfaces 265 a and 265 b are shown schematically. Eachembodiment can be used to achieve a somewhat different tissue effect inthe jaw structures of FIGS. 7A-8B and 9A-9B. For convenience, FIGS.10-14 illustrate first and second jaws 222 a and 222 b of the typedescribed in the text with reference to FIGS. 8A-8B, although it can beeasily understood that the jaws of FIGS. 10-14 can have a channel 280 asin the embodiment of FIGS. 9A-9B for receiving an I-beam member.

FIG. 10 illustrates a working end with first and second jaws 222 a and222 b wherein the electrosurgical energy-delivery surfaces 265 a and 265b comprise surface portions of first and second conductive bodies 285Aand 285B having opposing polarities indicated as positive polarity (+)and negative polarity (−). The first and second conductive bodies 285Aand 285B are coupled by electrical leads to Rf source 70 and controller75 as described above. In this embodiment, the inner surfaces oftranslatable member 240 are coated with an insulator layer to preventthe translatable member 240 from forming a conductive path between theopposing poles.

FIG. 11 illustrates an alternative embodiment wherein the first andsecond jaws 222 a and 222 b again include first and second conductivebodies 285A and 285B, respectively. A first electrosurgicalenergy-delivery surface 265 a again comprises a surface portion ofconductor or electrode 285A. The second energy-delivery surface 265 bcomprises a layer or body 288 of a pressure-sensitive resistive materialthat extends entirely across the jaw surface. The polymeric material hasa pressure-resistance profile wherein increased pressure reduces theresistance of body 288 as described in co-pending U.S. patentapplication Ser. No. 10/032,867 and Ser. No. 10/308,362. In use, theengagement of tissue will cause pressure against body 288 which willthereafter cause increased localized current flows through the body 288and within adjacent the tissue wherein engagement pressure is thehighest. In localized areas where engagement pressure is lower, lesscurrent will flow through that portion of body 288 and the adjacentengaged tissue. As tissue parameters such as tissue impedance changeduring the tissue sealing process, the dehydration of tissue will reduceits cross-section thereby reducing engagement pressure which therebyreduces current flow through the tissue. In this embodiment, thepressure-sensitive variable resistive body 288 can be understood to be aload-carrying material or body, which also has the ability to reducearcing and tissue desiccation at the energy-delivery surface 265 a.

The schematic view of FIG. 11 also can be use to illustrate relatedembodiments wherein first energy delivery surface 265 a comprises asurface portion of conductive body or electrode 285A indicated asnegative polarity (−). The second conductive body 285B has a surfacelayer or body 288 of a load-carrying material that comprises anothertype of partially resistive material in second surface 265 b. Such abody 288 includes partially resistive materials such as a positivetemperature coefficient of resistance material (PTCR) or a fixedresistance material, as disclosed in co-pending U.S. patent applicationSer. No. 10/032,867, Ser. No. 10/308,362 Ser. No. 10/032,867 and Ser.No. 10/291,286. The use of such a load-carrying body 288 has the abilityto reduce arcing at the energy-delivery surface 265 a, and furtherprovide passive (non-ohmic) heating of engaged tissue as the materialheats from internal resistance and from being heated by adjacentohmically-heated tissue.

FIG. 12 is a schematic view of an alternative embodiment wherein firstenergy-delivery surface 265 a comprises a surface portion of conductivebody or electrode 285A indicated as a negative polarity (−). The secondenergy delivery surface 265 b includes another portion of negativepolarity (−) electrode 285A in contact with a partially resistiveload-carrying material indicated at 290. Spaced apart from negativepolarity (−) electrode 285A is an opposing polarity (+) electrode 285Bthat is also in contact with the partially resistive load-carryingmaterial 290. Thus, the partially resistive load-carrying material 290is intermediate (and in contact with) the opposing polarity electrodes285A and 285B. The partially resistive load-carrying material 290preferably is a PTC material, a fixed resistance material, or a pressuresensitive material, as described above and in the previously identifiedrelated applications. Such load-carrying bodies 290 can reduce arcingand reduce tissue desiccation to enhance the creation of a high strengthseal in the engaged tissue.

FIG. 13 illustrates an alternative working end embodiment wherein firstand second jaws 222 a and 222 b again include first and secondconductive bodies or electrodes 285A and 285B that are exposed in therespective energy-delivery surfaces 265 a and 265 b. In this embodiment,the central portion 294 of surface 265 b is concave or recessed relativeto lateral body portions 295 and 295′ that comprise a load-carryingmaterial consisting of a PTCR material as described above. In thisembodiment, the jaw surfaces can be compressed together under extremelyhigh pressures which are useful for sealing tissue and any inadvertentcontact of surfaces 265 a and 265 b will not cause a short since contactof any region of the PTCR body 295 and 295′ with the opposing jaw willrapidly heat the contact point of the PTCR material and cause its localresistance to increase until that local portion is non-conductive. Itcan be understood that the central recessed portion 294 of surface 265 bis thus prevented from contacting the opposing polarity electrode of theopposing jaw no matter how high the compression of tissue.

FIG. 14 illustrates another embodiment wherein first and second jaws 222a and 222 b again include first and second conductive bodies orelectrodes 285A and 285B. In this embodiment, the first energy-deliverysurface 265 a is an exposed surface of electrode 285A but also can becarry any of the configurations of surfaces with load-carrying materialsdescribed above. The second surface 265 b has a central body portion 300of a pressure-sensitive resistive material as described previously inthe text relating to FIG. 11. The central polymeric body 300 issurrounded by lateral body portions 295 and 295′ that comprise aload-carrying material consisting of a PTCR material as described abovein FIG. 13. In use, the jaw surfaces can be compressed together and highpressures will cause the central polymeric body 300 to compress anddeliver current therethrough to the tissue. The PTCR body portions 295and 295′ will insure that any inadvertent contact of surfaces surface265 a and 265 b will not cause a short circuit as described in theembodiment of FIG. 13. In this embodiment, the pressure-sensitivevariable resistive body 300 will locally modulate current flow in tissueand prevent the possibility of arcing and tissue desiccation at theenergy-delivery surfaces.

Although particular embodiments of the present invention have beendescribed above in detail, it will be understood that this descriptionis merely for purposes of illustration. Specific features of theinvention are shown in some drawings and not in others, and this is forconvenience only and any feature may be combined with another inaccordance with the invention. Further variations will be apparent toone skilled in the art in light of this disclosure and are intended tofall within the scope of the appended claims.

What is claimed is:
 1. A surgical instrument, comprising: an elongateintroducer having a working end including openable-closeable first andsecond jaw members having curved distal portions that define a curvedtissue-engaging axis; a flanged member that is slidably carried by theintroducer, the flanged member moveable between a first non-extendedposition and second extended position wherein flanges slidably engagethe jaw members to move the jaws from an open position to a closedposition; and a flexible tissue-cutting member slidably carried by theintroducer, the tissue-cutting member moveable between a firstnon-extended position and a second extended position that extendsdistally beyond the flanged member and flexes.
 2. The surgicalinstrument of claim 1 wherein the flanged member in configured withlaterally-extending flanges.
 3. The surgical instrument of claim 1wherein the flanges slidably engage outwardfacing surfaces of the jawmembers.
 4. The surgical instrument of claim 1 wherein thetissue-cutting member includes a blade edge.
 5. The surgical instrumentof claim 1 wherein the tissue-cutting member includes an electrode. 6.The surgical instrument of claim 1 wherein at least one jaw memberincludes an electrosurgical energy-delivery surface for deliveringenergy to tissue.
 7. The surgical instrument of claim 6 wherein theelectrosurgical energy-delivery surface includes first and secondpolarity electrodes.
 8. The surgical instrument of claim 6 wherein theelectrosurgical energy-delivery surface includes a body having apositively or negatively sloped temperature-resistance profile.
 9. Thesurgical instrument of claim 6 wherein the electrosurgicalenergy-delivery surface includes a body that exhibits apressure-resistance profile wherein resistance decreases with pressure.10. The surgical instrument of claim 6 wherein the electrosurgicalenergy-delivery surface includes a body having a fixed resistance. 11.The surgical instrument of claim 6 wherein the electrosurgicalenergy-delivery surface of the first jaw member includes a first bodycomprising an electrode and a second body comprising a load-carryingmaterial that is partially resistive.
 12. The surgical instrument ofclaim 11 wherein the first body and the second body are in contact inthe energy-delivery surface.
 13. The surgical instrument of claim 6wherein the electrosurgical energy-delivery surface of the first jawmember includes a first body comprising spaced apart opposing polarityelectrodes and a second body comprising a load-carrying material that ispartially resistive.
 14. The surgical instrument of claim 13 wherein thefirst body and the second body are in contact in the energy-deliverysurface.
 15. The surgical instrument of claim 1 wherein the flangedmember comprises a plurality of axially-extending elements.
 16. Thesurgical instrument of claim 15 wherein the plurality ofaxially-extending elements are coupled by a flexible hinge joint. 17.The surgical instrument of claim 15 wherein the plurality ofaxially-extending elements are coupled by at least one flexible cable.